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Imai M, Sakuma Y, Kurisu M, Walde P. From vesicles toward protocells and minimal cells. SOFT MATTER 2022; 18:4823-4849. [PMID: 35722879 DOI: 10.1039/d1sm01695d] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In contrast to ordinary condensed matter systems, "living systems" are unique. They are based on molecular compartments that reproduce themselves through (i) an uptake of ingredients and energy from the environment, and (ii) spatially and timely coordinated internal chemical transformations. These occur on the basis of instructions encoded in information molecules (DNAs). Life originated on Earth about 4 billion years ago as self-organised systems of inorganic compounds and organic molecules including macromolecules (e.g. nucleic acids and proteins) and low molar mass amphiphiles (lipids). Before the first living systems emerged from non-living forms of matter, functional molecules and dynamic molecular assemblies must have been formed as prebiotic soft matter systems. These hypothetical cell-like compartment systems often are called "protocells". Other systems that are considered as bridging units between non-living and living systems are called "minimal cells". They are synthetic, autonomous and sustainable reproducing compartment systems, but their constituents are not limited to prebiotic substances. In this review, we focus on both membrane-bounded (vesicular) protocells and minimal cells, and provide a membrane physics background which helps to understand how morphological transformations of vesicle systems might have happened and how vesicle reproduction might be coupled with metabolic reactions and information molecules. This research, which bridges matter and life, is a great challenge in which soft matter physics, systems chemistry, and synthetic biology must take joined efforts to better understand how the transformation of protocells into living systems might have occurred at the origin of life.
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Affiliation(s)
- Masayuki Imai
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai 980-8578, Japan.
| | - Yuka Sakuma
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai 980-8578, Japan.
| | - Minoru Kurisu
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai 980-8578, Japan.
| | - Peter Walde
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
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2
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The Effect of the Osmotically Active Compound Concentration Difference on the Passive Water and Proton Fluxes across a Lipid Bilayer. Int J Mol Sci 2021; 22:ijms222011099. [PMID: 34681757 PMCID: PMC8540289 DOI: 10.3390/ijms222011099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022] Open
Abstract
The molecular details of the passive water flux across the hydrophobic membrane interior are still a matter of debate. One of the postulated mechanisms is the spontaneous, water-filled pore opening, which facilitates the hydrophilic connection between aqueous phases separated by the membrane. In the paper, we provide experimental evidence showing that the spontaneous lipid pore formation correlates with the membrane mechanics; hence, it depends on the composition of the lipid bilayer and the concentration of the osmotically active compound. Using liposomes as an experimental membrane model, osmotically induced water efflux was measured with the stopped-flow technique. Shapes of kinetic curves obtained at low osmotic pressure differences are interpreted in terms of two events: the lipid pore opening and water flow across the aqueous channel. The biological significance of the dependence of the lipid pore formation on the concentration difference of an osmotically active compound was illustrated by the demonstration that osmotically driven water flow can be accompanied by the dissipation of the pH gradient. The application of the Helfrich model to describe the probability of lipid pore opening was validated by demonstrating that the probability of pore opening correlates with the membrane bending rigidity. The correlation was determined by experimentally derived bending rigidity coefficients and probabilities of lipid pores opening.
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Hamsanathan S, Musser SM. The Tat protein transport system: intriguing questions and conundrums. FEMS Microbiol Lett 2019; 365:5000164. [PMID: 29897510 DOI: 10.1093/femsle/fny123] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/11/2018] [Indexed: 12/21/2022] Open
Abstract
The Tat machinery catalyzes the transport of folded proteins across the cytoplasmic membrane in bacteria and the thylakoid membrane in plants. Transport occurs only in the presence of an electric field (Δψ) and/or a pH (ΔpH) gradient, and thus, Tat transport is considered to be dependent on the proton motive force (pmf). This presents a fundamental and major challenge, namely, that the Tat system catalyzes the movement of large folded protein cargos across a membrane without collapse of ion gradients. Current models argue that the active translocon assembles de novo for each cargo transported, thus providing an effective gating mechanism to minimize ion leakage. A limited structural understanding of the intermediates occurring during transport and the role of the pmf in stabilizing and/or driving this process have hindered the development of more detailed models. A fundamental question that remains unanswered is whether the pmf is actually 'consumed', providing an energetic driving force for transport, or alternatively, whether its presence is instead necessary to provide the appropriate environment for the translocon components to become active. Including addressing this issue in greater detail, we explore a series of additional questions that challenge current models, and, hopefully, motivate future work.
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Affiliation(s)
- Shruthi Hamsanathan
- Department of Molecular and Cellular Medicine, College of Medicine, The Texas A&M Health Science Center, Texas A&M University, 1114 TAMU, College Station, TX 77843, USA
| | - Siegfried M Musser
- Department of Molecular and Cellular Medicine, College of Medicine, The Texas A&M Health Science Center, Texas A&M University, 1114 TAMU, College Station, TX 77843, USA
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Sengel JT, Wallace MI. Measuring the potential energy barrier to lipid bilayer electroporation. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630163 DOI: 10.1098/rstb.2016.0227] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electroporation is a common tool for gene transfection, tumour ablation, sterilization and drug delivery. Using experimental methods, we explore the temperature dependence of electropore formation in a model membrane system (droplet-interface bilayers), using optical single-channel recording to image the real-time gating of individual electropores. We investigate the influence of the agarose substrate on electropores formed in this system. Furthermore, by examining the temperature-dependent kinetics of pore opening and closure we are able to estimate a barrier to pore opening in 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) membranes to be 25.0 ± 8.3 kBT, in agreement with previous predictions. Overall these measurements help support the toroidal model of membrane electroporation.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Jason T Sengel
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Mark I Wallace
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK
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Ikari K, Sakuma Y, Jimbo T, Kodama A, Imai M, Monnard PA, Rasmussen S. Dynamics of fatty acid vesicles in response to pH stimuli. SOFT MATTER 2015; 11:6327-6334. [PMID: 26166464 DOI: 10.1039/c5sm01248a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate the dynamics of decanoic acid/decanoate (DA) vesicles in response to pH stimuli. Two types of dynamic processes induced by the micro-injection of NaOH solutions are sequentially observed: deformations and topological transitions. In the deformation stage, DA vesicles show a series of shape deformations, i.e., prolate-oblate-stomatocyte-sphere. In the topological transition stage, spherical DA vesicles follow either of the two pathways, pore formation and vesicle fusion. The pH stimuli modify a critical aggregation concentration of DA molecules, which causes the solubilization of DA molecules in the outer leaflet of the vesicle bilayers. This solubilization decreases the outer surface area of the vesicle, thereby increasing surface tension. A kinetic model based on area difference elasticity theory can accurately describe the dynamics of DA vesicles triggered by pH stimuli.
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Affiliation(s)
- Keita Ikari
- Department of Physics, Tohoku University, Aramaki, Aoba, Sendai 980-8578, Japan.
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Onsager's irreversible thermodynamics of the dynamics of transient pores in spherical lipid vesicles. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:473-81. [PMID: 26094069 DOI: 10.1007/s00249-015-1051-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/31/2015] [Accepted: 06/02/2015] [Indexed: 10/23/2022]
Abstract
Onsager's irreversible thermodynamics is used to perform a systematic deduction of the kinetic equations governing the opening and collapse of transient pores in spherical vesicles. We show that the edge tension has to be determined from the initial stage of the pore relaxation and that in the final state the vesicle membrane is not completely relaxed, since the surface tension and the pressure difference are about 25% of its initial value. We also show that the pore life-time is controlled by the solution viscosity and its opening is driven by the solution leak-out and the surface tension drop. The final collapse is due to a non-linear interplay between the edge and the surface tensions together with the pressure difference. We also discuss the connection with previous models.
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Sakuma Y, Imai M. From vesicles to protocells: the roles of amphiphilic molecules. Life (Basel) 2015; 5:651-75. [PMID: 25738256 PMCID: PMC4390873 DOI: 10.3390/life5010651] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 02/11/2015] [Accepted: 02/24/2015] [Indexed: 02/05/2023] Open
Abstract
It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life.
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Affiliation(s)
- Yuka Sakuma
- Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan.
| | - Masayuki Imai
- Department of Physics, Tohoku University, Aoba, Sendai 980-8578, Japan.
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Yi J, Barrow AJ, Yu N, O'Neill BE. Efficient electroporation of liposomes doped with pore stabilizing nisin. J Liposome Res 2013; 23:197-202. [PMID: 23594238 DOI: 10.3109/08982104.2013.788024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
CONTEXT Liposomes have a long history as passive and active drug carriers. Recently, a few methods have been realized to control the release from liposomes, including heating, ultrasound and laser. OBJECTIVE We report on a new approach to drive release from liposomes using electric fields. MATERIALS AND METHODS Liposomes were manufactured containing a high concentration of (quenched) 5-6 carboxyfluorescein dye. Nisin, a well-known amphiphilic peptide lantibiotic that works by stabilizing pores formed in cell membranes, was mixed in solution inside or outside the liposomes. The liposomes were then electroporated using a range of voltages, and assayed for increases in fluorescence due to release of dye. Release was measured against positive and negative controls, with positive control release driven by a strong detergent. RESULTS Our results demonstrate that the addition of nisin significantly reduces the electric field required to release the contents of liposomes, from 2000 V/m to approximately 200 V/m. This result proves that, in principle, electroporation (EP) of liposomes doped with small amounts of amphiphilic pore stabilizing peptides may be a practical means to drive release of liposomal contents in vivo. CONCLUSION Drug delivery from liposomes doped with amphiphilic peptides using EP is feasible. This technique could be developed into a potent adjuvant to tumor ablation using irreversible EP.
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Affiliation(s)
- Jiang Yi
- Department of Translational Imaging, The Methodist Hospital Research Institute, Houston, TX 77030, USA
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9
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Hamada T, Yoshikawa K. Cell-Sized Liposomes and Droplets: Real-World Modeling of Living Cells. MATERIALS 2012. [PMCID: PMC5449011 DOI: 10.3390/ma5112292] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent developments in studies concerning cell-sized vesicles, such as liposomes with a lipid bilayer and water-in-oil droplets covered by a lipid monolayer, aim to realize the real-world modeling of living cells. Compartmentalization with a membrane boundary is essential for the organization of living systems. Due to the relatively large surface/volume ratio in microconfinement, the membrane interface influences phenomena related to biological functions. In this article, we mainly focus on the following subjects: (i) conformational transition of biopolymers in a confined space; (ii) molecular association on the membrane surface; and (iii) remote control of cell-sized membrane morphology.
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Affiliation(s)
- Tsutomu Hamada
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa 923-1292, Japan
- Authors to whom correspondence should be addressed; E-Mails: (T.H.); (K.Y.); Tel./Fax: +81-761-51-1670 (T.H.); +81-774-65-6243 (K.Y.)
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, 1-3, Tatara Miyakodani, Kyotanabe, Kyoto 610-0394, Japan
- Authors to whom correspondence should be addressed; E-Mails: (T.H.); (K.Y.); Tel./Fax: +81-761-51-1670 (T.H.); +81-774-65-6243 (K.Y.)
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Zhang S, Nelson A, Beales PA. Freezing or wrapping: the role of particle size in the mechanism of nanoparticle-biomembrane interaction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:12831-12837. [PMID: 22717012 DOI: 10.1021/la301771b] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Understanding the interactions between nanoparticles (NPs) and biological matter is a high-priority research area because of the importance of elucidating the physical mechanisms underlying the interactions leading to NP potential toxicity as well as NP viability as therapeutic vectors in nanomedicine. Here, we use two model membrane systems, giant unilamellar vesicles (GUVs) and supported monolayers, to demonstrate the competition between adhesion and elastic energy at the nanobio interface, leading to different mechanisms of NP-membrane interaction relating to NP size. Small NPs (18 nm) cause a "freeze effect" of otherwise fluid phospholipids, significantly decreasing the phospholipid lateral mobility. The release of tension through stress-induced fracture mechanics results in a single microsize hole in the GUVs after interaction. Large particles (>78 nm) promote membrane wrapping, which leads to increased lipid lateral mobility and the eventual collapse of the vesicles. Electrochemical impedance spectroscopy on the supported monolayer model confirms that differently sized NPs interact differently with the phospholipids in close proximity to the electrode during the lipid desorption process. The time scale of these processes is in accordance with the proposed NP/GUV interaction mechanism.
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Affiliation(s)
- Shengwen Zhang
- Centre for Molecular Nanoscience, School of Chemistry, University of Leeds, Leeds, U.K
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11
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Ryham R, Berezovik I, Cohen FS. Aqueous viscosity is the primary source of friction in lipidic pore dynamics. Biophys J 2011; 101:2929-38. [PMID: 22208191 DOI: 10.1016/j.bpj.2011.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 11/04/2011] [Accepted: 11/08/2011] [Indexed: 10/14/2022] Open
Abstract
A new theory, to our knowledge, is developed that describes the dynamics of a lipidic pore in a liposome. The equations of the theory capture the experimentally observed three-stage functional form of pore radius over time--stage 1, rapid pore enlargement; stage 2, slow pore shrinkage; and stage 3, rapid pore closure. They also show that lipid flow is kinetically limited by the values of both membrane and aqueous viscosity; therefore, pore evolution is affected by both viscosities. The theory predicts that for a giant liposome, tens of microns in radius, water viscosity dominates over the effects of membrane viscosity. The edge tension of a lipidic pore is calculated by using the theory to quantitatively account for pore kinetics in stage 3, rapid pore closing. This value of edge tension agrees with the value as standardly calculated from the stage of slow pore closure, stage 2. For small, submicron liposomes, membrane viscosity affects pore kinetics, but only if the viscosity of the aqueous solution is comparable to that of distilled water. A first-principle fluid-mechanics calculation of the friction due to aqueous viscosity is in excellent agreement with the friction obtained by applying the new theory to data of previously published experimental results.
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Affiliation(s)
- Rolf Ryham
- Department of Mathematics, Fordham University, The Bronx, New York, USA
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12
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Dimova R. Membrane Electroporation in High Electric Fields. ADVANCES IN ELECTROCHEMICAL SCIENCES AND ENGINEERING 2011. [DOI: 10.1002/9783527644117.ch7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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13
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Ménager C, Guemghar D, Cabuil V, Lesieur S. Interaction of n-octyl β,D-glucopyranoside with giant magnetic-fluid-loaded phosphatidylcholine vesicles: direct visualization of membrane curvature fluctuations as a function of surfactant partitioning between water and lipid bilayer. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:15453-15463. [PMID: 20825201 DOI: 10.1021/la102532h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The present study deals with the morphological modifications of giant dioleoyl phosphatidylcholine vesicles (DOPC GUVs) induced by the nonionic surfactant n-octyl β,D-glucopyranoside at sublytic levels, i.e., in the first steps of the vesicle-to-micelle transition process, when surfactant inserts into the vesicle bilayer without disruption. Experimental conditions were perfected to exactly control the surfactant bilayer composition of the vesicles, in line with former work focused on the mechanical properties of the membrane of magnetic-fluid-loaded DOPC GUVs submitted to a magnetic field. The purpose here was to systematically examine, in the absence of any external mechanical constraint, the dynamics of giant vesicle shape and membrane deformations as a function of surfactant partitioning between the aqueous phase and the lipid membrane, beforehand established by turbidity measurements from small unilamellar vesicles.
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Affiliation(s)
- Christine Ménager
- UPMC Univ Paris 06, UMR 7195 PECSA, Physicochimie des Electrolytes, Colloïdes, Sciences Analytiques, F-75005 Paris France
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14
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Wang Y, Tang Y, Zhou Z, Ji E, Lopez GP, Chi EY, Schanze KS, Whitten DG. Membrane perturbation activity of cationic phenylene ethynylene oligomers and polymers: selectivity against model bacterial and mammalian membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:12509-12514. [PMID: 20586429 DOI: 10.1021/la102269y] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Poly(phenylene ethyneylene) (PPE)-based cationic conjugated polyelectrolytes (CPEs) and cationic phenylene ethynylene oligomers (OPEs) exhibit broad-spectrum antimicrobial activity, and their main target is believed to be the cell membrane. To understand better how these antimicrobial molecules interact with membranes, a series of PPE-based CPEs and OPEs with different side chains were studied. Large unilamellar vesicles with lipid compositions mimicking those of mammalian or bacterial membranes were used as model membranes. Among the CPEs and OPEs tested, the anionic CPE, PPE-SO(3)(2-) and the smallest cationic OPE-1 are inactive against all vesicles. Other cationic CPEs and OPEs show significant membrane perturbation ability against bacterial membrane mimics but are inactive against a mammalian cell membrane mimic with the exception of PPE-DABCO and two end-only-functionalized OPEs, which also disrupted a mammalian cell membrane mimic. The results suggest that the phospholipid composition of vesicles dominates the interaction of CPE and OPE with lipid membranes.
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Affiliation(s)
- Ying Wang
- Department of Chemical and Nuclear Engineering, Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico 87131-1341, USA
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Sakuma Y, Taniguchi T, Imai M. Pore formation in a binary giant vesicle induced by cone-shaped lipids. Biophys J 2010; 99:472-9. [PMID: 20643065 PMCID: PMC2905078 DOI: 10.1016/j.bpj.2010.03.064] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 03/24/2010] [Accepted: 03/29/2010] [Indexed: 12/18/2022] Open
Abstract
We have investigated shape deformations of binary giant unilamellar vesicles (GUVs) composed of cone- and cylinder-shaped lipids. By coupling the spontaneous curvature of lipids with the phase separation, we demonstrated pore opening and closing in GUVs. When the temperature was set below the chain melting transition temperature of the cylinder-shaped lipid, the GUVs burst and then formed a single large pore, where the cone shape lipids form a cap at the edge of the bilayer to stabilize the pore. The pore closed when we increased the temperature above the transition temperature. The pore showed three types of shapes depending on the cone-shaped lipid concentration: simple circular, rolled-rim, and wrinkled-rim pores. These pore shape changes indicate that the distribution of the cone- and cylinder-shaped lipids is asymmetric between the inner and outer leaflets in the bilayer. We have proposed a theoretical model for a two-component membrane with an edge of bilayer where lipids can transfer between two leaflets. Using this model, we have reproduced numerically the observed shape deformations at the rim of pore.
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Affiliation(s)
- Yuka Sakuma
- Department of Physics, Ochanomizu University, Bunkyo, Tokyo, Japan
| | - Takashi Taniguchi
- Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata, Japan
| | - Masayuki Imai
- Department of Physics, Ochanomizu University, Bunkyo, Tokyo, Japan
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Heuvingh J, Bonneau S. Asymmetric oxidation of giant vesicles triggers curvature-associated shape transition and permeabilization. Biophys J 2010; 97:2904-12. [PMID: 19948119 DOI: 10.1016/j.bpj.2009.08.056] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 08/03/2009] [Accepted: 08/17/2009] [Indexed: 01/05/2023] Open
Abstract
Oxidation of unsaturated lipids is a fundamental process involved in cell bioenergetics as well as in cell death. Using giant unilamellar vesicles and a chlorin photosensitizer, we asymmetrically oxidized the outer or inner monolayers of lipid membranes. We observed different shape transitions such as oblate to prolate and budding, which are typical of membrane curvature modifications. The asymmetry of the shape transitions is in accordance with a lowered effective spontaneous curvature of the leaflet being targeted. We interpret this effect as a decrease in the preferred area of the targeted leaflet compared to the other, due to the secondary products of oxidation (cleaved-lipids). Permeabilization of giant vesicles by light-induced oxidation is observed after a lag and is characterized in relation with the photosensitizer concentration. We interpret permeabilization as the opening of a pore above a critical membrane tension, resulting from the budding of vesicles. The evolution of photosensitized giant vesicle lysis tension was measured and yields an estimation of the effective spontaneous curvature at lysis. Additionally photo-oxidation was shown to be fusogenic.
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Affiliation(s)
- Julien Heuvingh
- Université Paris Diderot, Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR7636, Centre National de la Recherche Scientifique/Ecole Superieure Physique Chimie Industrielles Ville de Paris, Université Pierre et Marie Curie, Paris, France.
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17
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Role of membrane lipids for the activity of pore forming peptides and proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 677:31-55. [PMID: 20687479 DOI: 10.1007/978-1-4419-6327-7_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Bilayer lipids, far from being passive elements, have multiple roles in polypeptide-dependent pore formation. Lipids participate at all stages of the formation of pores by providing the binding site for proteins and peptides, conditioning their active structure and modulating the molecular reorganization of the membrane complex. Such general functions of lipids superimpose to other particular roles, from electrostatic and curvature effects to more specific actions in cases like cholesterol, sphingolipids or cardiolipin. Pores are natural phenomena in lipid membranes. Driven by membrane fluctuations and packing defects, transient water pores are related to spontaneous lipid flip-flop and non-assisted ion permeation. In the absence ofproteins or peptides, these are rare short living events, with properties dependent on the lipid composition of the membrane. Their frequency increases under conditions of internal membrane disturbance of the lipid packing, like in the presence of membrane-bound proteins or peptides. These latter molecules, in fact, form dynamic supramolecular assemblies together with the lipids and transmembrane pores are one of the possible structures of the complex. Active peptides and proteins can thus be considered inducers or enhancers of pores which increase their probability and lifetime by modifying the thermodynamic membrane balance. This includes destabilizing the membrane lamellar structure, lowering the activation energy for pore formation and stabilizing the open pore structure.
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18
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Portet T, Camps i Febrer F, Escoffre JM, Favard C, Rols MP, Dean DS. Visualization of membrane loss during the shrinkage of giant vesicles under electropulsation. Biophys J 2009; 96:4109-21. [PMID: 19450482 PMCID: PMC2712208 DOI: 10.1016/j.bpj.2009.02.063] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 02/20/2009] [Accepted: 02/20/2009] [Indexed: 11/26/2022] Open
Abstract
We study the effect of permeabilizing electric fields applied to two different types of giant unilamellar vesicles, the first formed from EggPC lipids and the second formed from DOPC lipids. Experiments on vesicles of both lipid types show a decrease in vesicle radius, which is interpreted as being due to lipid loss during the permeabilization process. We show that the decrease in size can be qualitatively explained as a loss of lipid area, which is proportional to the area of the vesicle that is permeabilized. Three possible modes of membrane loss were directly observed: pore formation, vesicle formation, and tubule formation.
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Affiliation(s)
- Thomas Portet
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, UMR 5089
- Laboratoire de Physique Théorique, Centre National de la Recherche Scientifique, UMR 5152, Université Paul Sabatier, Toulouse, France
| | - Franc Camps i Febrer
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, UMR 5089
| | - Jean-Michel Escoffre
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, UMR 5089
| | - Cyril Favard
- Institut Fresnel, Centre National de la Recherche Scientifique, UMR 6133, Marseille, France
| | - Marie-Pierre Rols
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, UMR 5089
| | - David S. Dean
- Laboratoire de Physique Théorique, Centre National de la Recherche Scientifique, UMR 5152, Université Paul Sabatier, Toulouse, France
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Wang Z, He X. Dynamics of vesicle formation from lipid droplets: mechanism and controllability. J Chem Phys 2009; 130:094905. [PMID: 19275422 DOI: 10.1063/1.3079097] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A coarse-grained model developed by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] is applied to investigate vesiculation of lipid [dipalmitoylphosphatidylcholine (DPPC)] droplets in water. Three kinds of morphologies of micelles are found with increasing lipid droplet size. When the initial lipid droplet is smaller, the equilibrium structure of the droplet is a spherical micelle. When the initial lipid droplet is larger, the lipid ball starts to transform into a disk micelle or vesicle. The mechanism of vesicle formation from a lipid ball is analyzed from the self-assembly of DPPC on the molecular level, and the morphological transition from disk to vesicle with increasing droplet size is demonstrated. Importantly, we discover that the transition point is not very sharp, and for a fixed-size lipid ball, the disk and vesicle appear with certain probabilities. The splitting phenomenon, i.e., the formation of a disk/vesicle structure from a lipid droplet, is explained by applying a hybrid model of the Helfrich membrane theory. The elastic module of the DPPC bilayer and the smallest size of a lipid droplet for certain formation of a vesicle are successfully predicted.
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Affiliation(s)
- Zilu Wang
- Department of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
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Mojzisova H, Bonneau S, Maillard P, Berg K, Brault D. Photosensitizing properties of chlorins in solution and in membrane-mimicking systems. Photochem Photobiol Sci 2009; 8:778-87. [PMID: 19492105 DOI: 10.1039/b822269j] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photosensitizing properties of three chlorins, meso-tetra(3-hydroxyphenyl)chlorin (m-THPC), chlorin e6 (Ce6) and meso-tetraphenylchlorin substituted by two adjacent sulfonated groups (TPCS(2a)) are compared in solution and when incorporated in dioleoyl-sn-phosphatidylcholine (DOPC) liposomes. In solution, the three chlorins possess a similar efficacy to generate singlet oxygen (quantum yield approximately 0.65). The formation of conjugated dienes was used to determine their ability to induce the peroxidation of methyl linoleate as a target of singlet oxygen. In ethanol solution, the apparent quantum yield for this process is the same for the three chlorins and its value agrees with that expected from the known rates for the decay of singlet oxygen and its reaction with methyl linoleate. When incorporated in liposomes, the order of efficacy is m-THPC > TPCS(2a) > Ce6. This order is tentatively assigned to the relative embedment of the photosensitizer within the lipidic bilayer, TPCS(2a) and Ce6 being anchored by their negative chains nearer to the water-lipid interface. The photoinduced permeation of the lipidic bilayer by these chlorins was investigated by measuring the release of carboxyfluorescein entrapped into DOPC liposomes. The charged chlorins, in particular TPCS(2a), are the most efficient, a result discussed in relation with the technology of photochemical internalization, PCI.
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Affiliation(s)
- Halina Mojzisova
- Laboratoire Acides Nucléiques et BioPhotonique (ANBioPhi), CNRS FRE 3207, 91030 Evry cedex, France
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Srividya N, Muralidharan S. Determination of the Line Tension of Giant Vesicles from Pore-Closing Dynamics. J Phys Chem B 2008; 112:7147-52. [DOI: 10.1021/jp7119203] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Narayanan Srividya
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Subra Muralidharan
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
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Abstract
Electric-field induced changes in structure and conductivity of supported bilayer lipid membranes (SLM) have been studied at submicroscopic resolution using atomic force microscopy and electrochemical impedance spectroscopy. The SLMs are formed on gold surfaces modified with mixed self-assembled monolayers of a cholesterol-tether and 6-mercaptohexanol. At applied potentials of < or =-0.25 V versus standard hydrogen electrode, the conductance of the SLM increases and membrane areas of <150 nm in size are found to elevate from the surface up to 15 nm in height. To estimate the electric field experienced by the lipid membrane, electrowetting has been used to determine the point of zero charge of a 6-mercaptohexanol-modified surface (0.19 +/- 0.13 V versus standard hydrogen electrode). The effects of electric fields on the structure and conductance of supported membranes are discussed.
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Dimova R, Riske KA, Aranda S, Bezlyepkina N, Knorr RL, Lipowsky R. Giant vesicles in electric fields. SOFT MATTER 2007; 3:817-827. [PMID: 32900072 DOI: 10.1039/b703580b] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This review is dedicated to electric field effects on giant unilamellar vesicles, a cell-size membrane system. We summarize various types of behavior observed when vesicles are subjected either to weak AC fields at various frequency, or to strong DC pulses. Different processes such as electro-deformation, -poration and -fusion of giant vesicles are considered. We describe some recent developments, which allowed us to detect the dynamics of the vesicle response with a resolution below milliseconds for all of these processes. Novel aspects on electric field effects on vesicles in the gel phase are introduced.
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Affiliation(s)
- Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Karin A Riske
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Said Aranda
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Natalya Bezlyepkina
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Roland L Knorr
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
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